Automatic control system



Feb. 18, 1964 H. L. BAUMBACH ETAL 3,

AUTOMATIC CONTROL SYSTEM Original Filed Sept. 1, 1955 2 Sheets-Sheet 1INVENTORS. Q fl/IRA AA/ A. nu/valve BY HOW/4R0 M. L/rn:

ATTORNEY Feb. 18, 1964 H. L. BAUMBACH ETAL 3,121,785

AUTOMATIC CONTROL SYSTEM Original Filed Sept. 1, 1955 2 Sheets-Sheet 2 e#67 2 D. C.

' e l T IN VEN TORS.

United States Patent 3,121,785 AUTGMATHI CGNTRQL SYSTEM Harlan L.llaumhach and Howard M. Little, Los Angeies, Calii, asslgnors, by mesneassignments, to hell Howell tcornpany, a corporation of lllinois()riginal application Sept. ll, 1%5, Sci. No. 531,879, new Patent No.2,935,923, dated May lit), sass. Divided and this application May 26,1953, Ser. No. 737,964

5 Claims. (Cl. 235-616) This invention relates to electrical controlsystems, and more particularly to an improved automatic electricalcontrol system for effecting periodic, pro-selected operation of aplurality of controlled elements.

This application is a division of our co-pending application, Serial No.531,879, now Patent No. 2,935,923 filed September 1, 1955, and entitledAutomatic Photographic Printing Machine.

Briefly stated, automatic control systems of the type to which thisinvention pertains are equipped with a control member which may bepreset with sets of control information each corresponding to apreselected one or preselected ones of the controlled elements, asensing device for sensing the sets of control information, means forrelatively advancing the preset control member and sensing device pastone another to successively align the control sets with the sensingdevice, and a control circuit between the sensing device and controlledelements for selectively operating the latter in accordance with thecontrol information contained in the control sets.

One type of control member which is widely used in automatic controlsystems of this nature consists of a tape, the control sets of whichcomprise coded sets of control indications, such as perforations.Generally, these control tapes have a blank leader portion preceding thefirst coded control set.

In order to condition the control system for operation, it is necessaryto initially feed this leader portion of the tape past the tape readerto align the first control set with the reader. To the end of facilityand speed of operation of the control system, it is highly desirable toaccomplish this initial advancing of the control tape, or other controlmember having a blank leader, automatically. Moreover, since the controlsystem is not conditioned for proper operation until this initialadvancing of the con trol member is completed, the control system ispreferably provided with interlock means for deactivating the controlledmachine until the first control set is aligned with the reader.

Sensing operation of tape sensing devices generally involves theselective establishment of one or more electrical contacts, eachcorresponding to a particular controlled element, in accordance with thecontrol information in the control sets. The controlled elements, inturn, are operated in response to the establishment of their respectivecontacts.

in the existing control systems, these contacts are, in most cases, indirect circuit with the controlled elements. This arrangement possessesan inherent disadvantage which is especially serious in certainapplications, such as in the illustrative use of the present controlsystem for controlling printing light intensity in a film printer.

Thus, with such a direct circuit arrangement, preselected actuation ofthe controlled elements, in accordance with the control information of aparticular control set, is interrupted in the event of failure of acontact. Further, during relative advancing of the control member fromone control set to the next, all of the sensing contacts areinterrupted. Accordingly, all of the controlled elements becomemomentarily deactivated.

It is desirable, therefore, that the control systems embody some type ofmemory system between the sensing 3,121,786 Patented Feb. 18, 1964device and controlled elements for maintaining the preselected actuationof the controlled elements corresponding to each control set duringrelative advancing of the control member to the next control set as Wellas in the event of failure of a contact.

While automatic control systems, having such memory systems have beendevised, the memory period of the memory systems was relatively short.On the other hand, it is often desirable or necessary that the memorysystem be operative for a relatively long and indefinite period of time,such where the relative advancing of the control member occursinfrequently or at a slow speed.

A final desirable feature of automatic control systems of the presenttype is that they be capable of automatically terminating operation of acontrolled machine in response to completion of the sequence ofoperations recorded on the control member.

With the foregoing preliminary discussion in mind, a broad object ofthis invention may be stated as being the provision of an improvedautomatic control system of the character described.

A more specific object of the invention is the provision of an automaticcontrol system of the character described wherein initial relativeadvancing of the presettable control member of the system past thesensing device, to align the latter with the first control set of thecontrol member, is accomplished automatically.

Another object is the provision of an automatic conrol system as in theforegoing which is capable of deactivating the controlled machine duringinitial relative advancing of the control member to the first controlset.

Yet another object is the provision of an automatic control system ofthe character described having an improved memory system for maintainingeach preselected actuation of the control system for indefinite periodsof time.

A further object is the provision of an automatic control system of thecharacter described which is effective to automatically stop acontrolled machine upon completion of the sequence of operationsrecorded on the preset control member.

Yet a further object is the provision of an automatic control system ofthe character described which operates to efieot preselected actuationof a plurality of controlled elements in response to the coding orpresetting of each of a series of control sets on a control member andwherein automatic initial advancing of the control member and shut downof the equipment occurs in response to predetermined conditions of thecontrol member.

A still further object of the invention is the provision of an automaticcontrol system of the character described which is ideally suited forcontrolling printing light intensity in a film printer.

Other objects, advantages and features of the invention will becomereadily apparent as the description proceeds.

For illustrative purposes, the invention will be described Withreference to its use in motion picture film printing machines forcorrecting the printing light intensity from one scene to the next.

In the illustrated embodiment of the invention, a control tape,prepunched with coded sets of light change perforations in accordancewith the varying densities of the several scenes of a negative film, isintermittently advanced past a tape reader, in response to cueingnotches in the film, to sequentially align said perforation sets withthe reader. The control system of the invention incorporates a series ofrelays which are selectively operated, in accordance with the coding ofeach set of perforations, to establish predetermined light intensitiesin the film printing machine.

The control system is operative in response to the absence ofperforations in the blank leader portion of the 2 tape to initiallycontinuously advance the tape past the reader to a first set ofperforations. Also embodied in the present control system are means forstopping the printer automatically when the tape is advanced to aperforation set having a predetermined coding.

A highly important and advantageous feature of the control systemresides in the provision of a memory sys tem which has a memory periodof indefinite length and which is operative to maintain a given printinglight intensity even though the reader contacts fail and duringadvancing of the tape to align a following perforation set with thereader.

A better understanding of the invention may be had from the followingdetailed description taken in connection with the annexed drav ings,wherein:

FIG. 1 is a schematic circuit diagram of the invention in a filmprinter;

FIG. 2 is an enlarged showing of the control tape used in the invention;and

FIG. 3 schematically illustrates a modified form of light change deviceto be used with the control system.

Referring first to FIG. 1, the nume 'al 19 denotes the film feedmechanism of a film printer including a sprocket wheel 11 and drivemotor 12 therefor for advancing a negative film strip N and a positivefilm strip P through a beam of light from a source 13. The beam of lightpasses through the negative film strip and impinges on the positive filmstrip so as to produce on the latter latent positive images of thenegative images contained on the negative film strip N.

In the printer illustrated in FIG. 1, the intensity of the beam of lightfrom source 13 at the film strips P and N is controlled by a variabledensity light filter arrangement 14 including a series, shown as five innumber, of varying density light filter elements 15, separatelydesignated as a, b, c, d, e. These filter elements are normally disposedin the path of said beam, between source 13 and the film strips P and N,and adapted to be selectively removed therefrom either singly or incombination. Each of the .filter elements 15 is of differentpredetermined light density so that by such selective individual orcombined removal of the filters, different light intensities may be pro-.vided at the film strips, as will presently be more fully explained.

Associated with each of the filter elements 15' is a solenoid actuatingelement 16 which when energized will move its respective filter elementout of the path of the printing light beam. The filter elements arenormally retained in a position in such path, for example, by means ofbiasing springs 17 on the solenoids 16.

Automatic selective energization of the solenoids 16 to achievepredetermined light changes during the operation of the printer It isaccomplished by operation of the present control system, generallydenoted at 18. This control system comprises a preformed control member19 (see also FIG. 2), for example, which may be a tape punched with sets26 of light change perforations, and an electrical circuit 21 includinga tape reader or sensing device 22 for sensing the perforations or otherindications in each of the sets 20 in the control tape 19 and effectingselective cnergization of the light filter solenoids 16 in accordancewith the perforations present in any given one of the perforation sets20. Solenoids 16, then, comprise the controlled elements which are to beselectively actuated by the present control system.

As shown in FIG. 2, each of the perforation sets 20 has five positions,designated as a, b, c, d, e, in which a perforation may be formed, eachof said positions being identified with the correspondingly lettered oneof controlled elements, namely the light filter solenoids 16. As willpresently be more fully described, the arrangement of circuit 21 is suchthat a perforation in position a will result in cnergization of filtersolenoid 150, a perforation in position b will result in energization offilter solenoids 16b, and so forth.

While each of the perforation sets 2% have been illustrated ascontaining a maximum of five perforations for the selective control offive light change filters, it will be apparent that the maximum numberof perforations in each of the sets 29 may be varied according to thenumber of elements to be controlled.

Circuit 21 of the present control system will now be described ingreater detail. It will become readily apparent as the descriptionproceeds that various types of control members and sensing devices,other than a punched tape and tape reader, as illustrated, may be usedin the control system. Where a punched tape is utilized as the controlmember 19, as shown, sensing device 22 may comprise any conventionalpunched tape reader. For the purpose of illustration, the reader 22 isshown as comprising a metallic platen 23 and five flexible contactbrushes 24 individually designated as a, I), c, (I, 0, arranged tonormally contact the platen. As will be seen, tape 19 is, duringoperation of the system, fed between platen 23 and brushes 24 so thatcontact will be established between the brushes and the platen only inthe presence of a corresponding perforation in the tape.

Platen 23 is connected, through leads 25a, 25b, and a series connectedswitch 26, to one terminal of an AC. supply 27. Brushes 24a through 24-0are connected, respectively, through leads 28, 29, 30, 31 and 32 to oneterminal of a series of five relay coils 33a33e. The other terminals ofthe coils 33 are connected through a common lead 34 and a lead 35 to theother terminal of the AC. supply 27.

It will be apparent from the foregoing description that when switc 26 isclosed, relay coils 33 will be energized whenever their respectivebrushes 24 contact the platen 23.

Relays 33 comprise a first set of normally open, series connectedcontacts mini-36c. When all of these latter contacts are closed bysimultaneous energizing of the five relays 33, a circuit is completedfrom lead 25a through leads 25a, 37, contacts 36, lead 38, a relay coil39, and lead 49 to the other terminal of supply 27. Thus, when switch 26and all of the contacts 36 are closed, relay 39 energizes to open itsnormally closed contacts 41. These contacts 41 are connected in theenergizing circuit 42 for film feed motor 12 so that energization of therelay 39 results in stoppage of the feeding of the film strips N and Pthrough the printer 10. Arranged in shunt with the relay contacts 35 isa circuit comprising a lead extending from lead 38 for relay 39 to oneterminal of a switch 44, and a lead 45 extending from the other terminalof switch 44 to AC. supply lead 2511. It will be seen that when switch44 is closed, relay contacts 36 are bypassed and relay 3 energizes. Thisswitch 44 is initially closed to prevent the printer motor 12 fromstarting, for reasons to be presently described.

Relays 33 comprise a second set of normally open, parallel connectedcontacts ifia le. Closing of any one of these contacts by energizationof its respective relay coil 33 completes a circuit from one terminal ofAC. supply 27, through leads 25b, 25a, 47, contacts 46, lead 48, a relaycoil 4-9, and leads 34 and 35 to the AC. supply 27 to energize the relay49.

Relay :9 comprises a first set of normally open contacts 59 which, whenclosed by energizing of coil 4-), connect lead 47 to a lead 51. Lead 51extends to a third set of normally open parallel arranged contacts52a-5Ze of the relays 33. These latter relay contacts 52 are connected,through leads 53, 54, 55, 56 and 57, respectively, to one of theterminals of a second set of five relay coils Ella-58c. The otherterminals of coils 53a-58e are connected to lead extending to the A.C.supply. Thus, it will be evident that encrgization of any one of thefirst set of five relays 33 results in the cncrgization of thecorresponding one of the second set of five relays 58. This latterenergizing circuit may be traced from one terminal of the A.C. supply2-7, through leads b, 25a, 4?, contacts 5% closed, as above describedupon energization of any one of the relays 33, lead 51, contacts 52corresponding to the energized relay 33, relay coils 5-8, and thence tothe other terminal of A.C. supply 27 through lead 35.

A series of normally open lock-in contacts 59a-59e are associated withthe second set of five relays 53 for maintaining the latter in anenergized state once they are energized by energization of thecorresponding relays 33. To this end the lock-in contacts 59rL-59e haveone terminal connected via leads 6t), st, 62, 63 and 6d, respectively,to the upper ends of their associated relay coils Sitar-58c. The otherterminals of contacts 59a59e are connected through leads 6%, all, 62.,63, 64, respectively, to a series of five normally closed, parallelarranged contacts titles-65c, in an A.C. pulse circuit 66'. Contacts 65are connected through leads 67, 47, 25a and 25b to one terminal of A.C.power supply 2'7. Thus, with the lower ends of coils 58 connected to theother terminal of supply TF7 and with the contacts 65 closed, closing ofany one of the lock-in contacts 59 by energizing of the correspondingrelay operates to lock such corresponding relay in its energizedcondition. As will presently be more fully described, the lock-incontacts 59 and their associated leads comprise the previously mentionedmemory circuit which constitutes a highly important feature of theinvention, Thus, during advancing of tape 19 from one set 29 ofperforations to the next following erforation set 2i), contact be tweenall of the brushes and the platen Z3 is momentarily broken. In theabsence of the present memory circuit, therefore, all of the filters 15would be momentarily returned to their normal positions in the path ofthe printing beam so that during this period, the positive film P wouldbe improperly exposed.

The lock-in contacts 59 act to maintain those filter solenoids 16,corresponding to the perforations in a preceding perforation set,energized during advancing of the tape 15. Accordingly, during thistransit of the tape, the corresponding filters 15 remain out of the pathof the beam and the positive film will be properly exposed. Moreover,these lock-in contacts act to maintain the predetermined printing beamintensity, even though the contacts 24 of the tape reader tail afterinitial contact with the platen 23.

It will be seen that the lock-in contacts 59 remain operative so long asthey are supplied with energizing current. Thus, the present memorycircuit may be considered to have a memory period of. indefinite length.This prolonged memory period may be important, for example, whererelatively slow or widely varying tape advance speeds are used undervarious conditions or wh re a reader contact fails at the beginning ofprinting a relatively long scene. Also the printer may be stopped andthe reader rendered inoperative for prolonged periods of time andsubsequently their operation continued without interruption of thememory circuit.

The A.C. pulse circuit as provides for opening the lock-in contacts 59under certain hereafter described conditions. To this end the contacts65 comprise a relay whose coil 63 has one terminal connected to the A.C.supply lead 34 and the other terminal connected through a lead 69, a setof normally closed contacts 7d of a relay 71, and a second set ofnormally open contacts 72 of the relay 49 to lead 4'7. One terminal ofrelay coil 71 is connected to the A.C. supply lead 34 while its otherterminal is connected through a lead 73- to normally open contact points73 and '73 associated with normally closed contacts 65 and 70. Contacts73 close upon opening of contacts 7%, by energizing of coil 71, andcontacts 73" close upon opening of contacts 65 by energization of relay6%. Operation of this lock-in releasing A.C. pulse circuit will bedescribed presently.

' Associated with the relay coils 58 are a second set of normally opencontacts 74a74e. The upper terminals, as viewed in the drawing, of thesecontacts are connected through a common lead 75 to one terminal of A.C.power supply 27. The lower terminals of the contacts 74 are connectedthrough leads '77, 78, 79, 8t) and 81 to the lower ends of light changesolenoids 16. The upper ends of these latter solenoids are connected tothe other terminal of supply 27 through a common lead '82. Printinglight 13 may be energized from a DC. supply as indicated.

As will be more fully described, contacts 74 effect the actual lightintensity changes in the printer. Thus, closing of any one of thecontacts 74 by energizing of the associated relay 58 completes a circuitfrom the supply 27 to the corresponding light filter solenoid 16 toenergize the latter and move the corresponding filter 15 out of the pathof the printing light beam.

Indicated generally at 84 is any conventional mechanism for advancingtape 19 past reader 22 during operation of the system. This mechanism isschematically illustrated as comprising a sprocket wheel 85 formed withteeth -86 for engaging sprocket holes 87 in the tape. Wheel 85 iscoupled to a ratchet wheel 88 by a shaft 89 so that rotation of wheel 88imparts rotation to wheel 85.

A spring biased pawl 9%, arranged to engage the teeth of ratchet wheel88, is operated by a solenoid 91. The arrangement is such that each timesolenoid 1 is energized, pawl 9G is operated downwardly to step ratchetwheel 88 and cause advancing of tape 19 through a predetermineddistance. This distance is made equal to the spacing between the sets 20of perforations in the tape.

Solenoid 91 is energized through a DC. circuit, whose conductors are, inthe interest of clarity, illustrated by relatively fine lines ascompared to the conductors of the A.C. circuit heretofore described.

This D.C. energizing circuit comprises a DC. pulse circuit 92 which, inthe absence of any perforations in tape 19, feeds the tape advancesolenoids hit, a series of pulses for continuously advancing the tapepast the tape reader 22 to the first set of perforations. D.C. pulsecircuit 92 comprises a first coil 93 shunted by a first condenser 94 anda second coil 95 shunted by a pair of condensers 96.

These coils and condenser 93% have one terminal connected through acommon lead 97 to one terminal of a DC. supply 98. *First coil andcondenser 93 and 94 have their other terminal connected to the otherterminal of the D.C. supply 9% through a circuit which may be tracedthrough lead 9%, a set of normally closed contacts 1% of the first coil93, lead ltll, a set of normally closed contacts m2 of the second coil95, lead 1%, a third set of series connected, normally closed, contactsltldcz-lMe of the relays 58a-58e, lead Hi5, switch lii, lead 107, andswitch 168 to said other terminal of the DC. supply 98. Switches 44 and1th? and switches 26 and 108 are tied together for simultaneousoperation thereof, as indicated.

The other terminal of the shunt connected coil and condenser assembly 95and 96 is adapted to be connected to DC. supply connected lead 1&5 byclosing of a second set of normally open contacts it}? operated by firstcoil 93. A third set of normally open contacts 110 of this latter coil,when closed, connect lead to a lead 11 extending to one terminal of afilm-operated switch 112. The other terminal of this latter switch isconnected, via leads 113 and 107, to the DC. supply 98. The tape advancesolenoid 91 is series connected in a lead 91 tied at opposite ends toleads 111 and 97.

Operation Negative film N will have been initially viewed in itsentirety by an operator who will form in the film, at each point where achange in printing light intensity is to occur, a notch 114.Simultaneously he will form in the control tape 19, properly coded sets20 of perforations wherein the perforations will be present in one ormore of the previously mentioned positions ae depending on which of thefilters must be removed from the path of the printing light beam toyield the desired light intensity at the film.

The leading end of this prepunched tape is inserted into reader 22 toengage sprocket holes 87 with the sprocket wheel 85, the tape passingbetween the platen 23 and brushes 24. Normally the first set of lightchange perforations will be spaced some distance from the leading end ofthe tape so that the latter must be initially advanced a substantialdistance through the reader to align the first set of perforations withthe reader brushes 24.

To effect this initial advancing of the tape, switches 44 and 106 aremoved to their right hand, closed position, and switches 26 and 108 areclosed to energize the control circuit for the tape advancing mechanism34. A.C. supply 27 will thereby also be connected to the control circuitfor the light filter solenoids 16 and film feed motor 12. However, sincethe blank leader portion of the tape 19 now separates brushes 24 fromplaten 23, relays 33 and 58 remain deenergized. Moreover, closing of theswitch 44 completes a circuit through the motor control relay 39, sothat when switch 26 is closed, relay 39 energizes to open contacts 41for film feed motor 12. The printer 10, therefore, remains inoperative.

Since relays 58 are deenergized, contacts 104 are closed so that acircuit may be traced from the right hand terminal of DC. supply 98,through lead 97, coil 93, lead 99, contacts 100, lead 101, contacts 102,lead 103, contacts 104, lead 105, switch 106, lead 107, switch 103 tothe other terminal of the DC. supply. Coil 93 is thereby energized toclose its normally open contacts 109 and 110 and open its normallyclosed contacts 100.

Closing of contacts 110 completes a circuit from DC. supply 98 throughswitch 108, lead 107, switch 106, lead 105, contacts 110, lead 111, lead91, tape advance coil 91, and thence back to the other terminal ofsupply 93 through lead 97. Coil 91 thus energizes to actuate the tapeadvance mechanism 84 and cause advancing of the tape 19 a distance equalto the spacing between adjacent sprocket holes 87.

Simultaneously with the closing of contacts 110, contacts 100 open tobreak the circuit between coil 93 and DC. supply 98 and contacts 109close to complete a circuit from DC. supply connected lead 97 throughcoil 95 to DC. supply lead 105. Coil 95, therefore, energizes and itsnormally closed contacts 102 open.

Although the energizing circuit to coil 93 is broken by opening of itscontacts 100, discharge of condenser 94 through said coil maintains thelatter energized sufficiently long to deliver a DC. pulse to tapeadvance coil 91 and effect opening of contacts 102 of coil 95.

After condenser 94 has discharged through coil 93, to a given value, itscontacts 109 and 110 reopen and its contacts 100 reclose. Reopening ofcontacts 109 breaks the energizing circuit to coil 95, but the latterremains energized for a brief period of time sufficient to allow theadvance mechanism to return to its normal position under the action ofthe biasing spring therein.

Accordingly, reclosure of contacts 100 does not instantaneously resultin cnergization of coil 93 inasmuch as contacts 102 will be held open bythis prolonged energization of the coil 95.

After condensers 96 have discharged through their associated coil 95 toa predetermined value, contacts 102 reclose and coil 93 reenergizes torepeat the abovedescribed cycle. Thus, it may be seen that the DO pulsecircuit 92 operates to deliver a series of DC. pulses to the tapeadvance coil 91 and the tape 19 will be con tinously intermittentlyadvanced past the reader 22.

This intermittent advancing of the tape continues until the first of thesets 20 of light change perforations become aligned with the readerbrushes 24. At that time, one or more of the brushes 24, depending onthe perforations present in the first set, contact the platen 23 throughsuch perforations. As will now be described, this contact of any one ofthe brushes with the platen results in energizing of the correspondingrelay 58 and opening of its contacts 104. Opening of any one of thecontacts 104 breaks the energizing circuit to the coil 93 in DC. pulsecircuit 92 and the latter will cease to operate. Thus, the tape willstop when the first set fo perforations becomes aligned with the readerbrushes 24.

This initial contact between one or more of the reader brushes 24 andplaten 23 also establishes an initial printing light intensity at thefilm strip N in the following manner. Assuming that the firstperforation set 20 on the tape 19 contains only a perforation inposition a so that only brush 24a contacts the platen, relay coil 33::becomes energized and its normally open contacts 36a, 46a and 52a close.

Closure of contacts 460 places the AC. supply 27 across relay coil 49 toenergize the latter and close its normally open contacts 50. Closure ofcontacts 50 and 52a completes a circuit from A.C. supply 27 throughrelay coil 58a to energize the latter and close its normally opencontacts 59a and 74a and open its normally closed contacts 104a. Asdescribed above, opening of contacts 104a results in interruption of theDC. pulse circuit 92.

Contacts 59:: act to lock-in relay coil 58:: so that the latter remainsenergized and its contacts 74:: remain closed. These latter contacts 74acomplete a circuit from the right hand terminal of AC. supply 27 throughlead 75, contacts 74a, lead 77, light filter solenoids 16a, and lead 82to the other terminal of source 27. Solenoid 16a is thus energized toretract light filter 15a out of the printing beam.

Similarly, if the first of the perforation sets 20 contains perforationsin any of the other positions b-e, the corresponding filter elements15b15e will be removed from said beam.

Thus, the intensity of the light impinging on the film will be increasedin accordance with the light density of a single filter, where only onefilter is removed, or in accordance with the combined light density ofseveral filters where more than one filter is removed from the lightbeam.

Printing light 13 is now energized and simultaneously switches 44 and106 are operated to their open position. Opening of switch 4-4 resultsin breaking of the previously described energizing circuit for motorrelay 39 whereupon its normally closed contacts 41 reclose to complete acircuit from the left hand terminal of AC. supply 27, through switch 26,leads 25b and 42, feed motor 12, contacts 41, and lead 40 to the righthand terminal of supply 27.

The positive and negative film strips P and N are fed, by operation ofmotor 12, in the direction indicated to successively expose the framesof the negative film to the beam which now has an intensity,corresponding to the perforations present in the first perforation set.

As the first one of the notches 114 passes the interrupter switch 112,the latter is momentarily closed, by movement of the roller carried onthe switch rocker arm into the notch, and a circuit is momentarilyestablished from the left hand terminal of DC. supply 98, through nowclosed switch 108, leads 107 and 113, switch 112, leads 111 and 91, tapeadvance solenoid 91 and lead 97 to the right hand terminal of the DC.supply.

Tape 19 is thereby advanced to align the second set of perforations 20with the reader brushes 24. Contact with platen 23 of those of thebrushes 24a24e corresponding to perforations present in the second setof perforations results in the energization of the corresponding ones ofthe light filter solenoids 160460 and removal of the associated filterelements -152 from the path of the printing light beam to achieve theproper beam intensity for the second scene of the negative film.

If a perforation in one set of perforations is absent from the nextfollowing set, A.C. operation of pulse circuit 66 releases the loclcincontacts 59 associated with that perforation to permit return of thecorresponding filter element 15 to its normal position.

Thus, for example, assuming that the first perforation set contained aperforation in position a and that the second perforation set containeda perforation only in position 15, relays 53b and 58b energize due tocontact of brush 24b with platen 23. Resultant closing of contacts 4d];of relay 33b energizes relay 45 to close its normally open contacts 72whereupon a circuit may be traced from lead 47, extending to the lefthand terminal of AC. supply 27, through contacts 72, normally closedcontacts 74), lead 69, relay coil 63 to lead 34 extending to the otherterminal of the supply 27. Relay as is thereby energized and itsnormally closed contacts 6*5a65e open, thus breaking the energizingcircuit through lock-in contacts 59a for relay This latter relay nowbecomes deenergized and its contacts 74a and lock-in contacts 5% openallowing light filter a to be reinserted under the action of theassociated biasing spring 17. Relay 58a, therefore, remains deenergizeduntil subsequent contact is established between brush 24a and platen 23due to the presence of a perforation being present in position a in asucceeding set of perforations.

Relay 58b, however, remains energized by virtue of the contact betweenbrush Nb and platen 23. Simultaneously with the opening of contacts 65aby energizing of coil 68, normally open contacts '73" of coil 68 closeto complete a circuit from A.C. supply lead 67 through contacts 73, lead73, relay coil 71 to lead 34 to the right hand terminal of the supply27.

Relay coil 71 is thereby energized and its normally closed contacts 76open to break the energizing circuit to relay 68 and allow its contacts6=5a-65e to return to their normal closed condition whereupon thelock-in contact 59b of relay coil 58b becomes operative to maintain thelatter coil energized during subsequent advancing of the tape and eventhough the contact between brush 24b and platen 23 subsequently fail.

Contacts 73 of relay coil 71 close simultaneous with the opening of itscontacts 76 so that coil 71 is locked in energized condition as long ascontacts 72 are retained closed by energization of relay &9. This latterrelay is momentarily deenergized during advancing of tape 19 from oneset of light change holes 2d to the next, since during this transit noneof the brushes 24 will contact the platen and accordingly all of thecontacts as open momentarily. This momentary deenergizing of coil 49opens contacts 72 and deenergizes coil '71. This allows contacts 73 ofrelay 71 to reopen and contacts 70 to reclose so as to condition theA.C. pulse circuit for repetition of the above described operation whenthe next set of light change holes in tape 1% become aligned with thebrushes 24.

Tape 19 will continue to be advanced to sequentially align the sets 2dof light change holes in the tape with the brushes 24 each time one ofthe cueing notches 114 in the film passes interrupter switch 112. Aseach of said sets of holes '20 become aligned with the brushes, thesystem operates in the manner described above to remove from between theprinting light source 13 and the film one or more of the light filters15 in accordance with the perforations present in each set.

The system will continue to operate in this manner until the tape isadvanced to a position wherein the set of perforations aligned with thereader 22 contains a perforation in each of the positions ae. Thiscondition of all five perforations being present results in energizingof all five relays 33 and, accordingly, in closure of all five contacts36a-36a A circuit is then completed from A.C. supply 27 through motorrelay 39. The latter 1G energizes to open its normally closed contacts41 and stop film feed motor 12.

Tape 19 will be deliberately punched with all five perforations to stopthe printer at the completion of a printing operation.

The present control system may also be used with a printer having avariable resistance printing light change in lieu of the variabledensity filter arrangement just described. In this variable resistancearrangement, shown in FIG. 3, contacts Ma /4e of relays 58 operate toremove varying amounts of resistance in series with the printing lamp13. In FIG. 3, only the contacts 74, re sistance element 115, lamp 13and a DC. supply 116 have been illustrated, in the interest of clarity,it being understood that the remainder of the light change system wouldbe identical to that described.

As shown in H6. 3, with all of the contacts 74a-74e open, which positionthey will occupy when all of the relays 33 and 53 are deenergized due tono light change perforations being present in the tape 19, a circuit maybe traced from he left hand terminal of supply M6, lamp 13, andresistance element to the right hand terminal of said supply. Theintensity of the light emitted from the lamp will, therefore, have aminimum value.

As shown, the contacts 74a'7 le are series connected and are tapped tothe resistance element 115 at five points designated as ae, the firstcontact 74a having one terminal tapped at a to the lead extending to thesupply 116. The distance between taps gradually increases so that, forexample, the resistance value between taps a and b will be a multiple ofthe resistance Value between taps a and a, the resistance value betweentaps b and 0 will be a multiple of that between taps a and b, and soforth.

The arrangement is such that when contacts 74a are closed, theresistance between taps a and a is shunted, when contacts 74b are closedthe resistance between taps a and b is shunted, and so on. Thus,successive closing of the contacts 7441-742, in that order, will produceincremental increases in the printing light intensity, which intensitymay be further increased by closing two or more of the contacts indesired combination.

The operation of the system when incorporating the above describedresistance change is the same as that previously set forth with respectto the system utilizing variable density light filter elements. Nofurther description thereof is, therefore, deemed necessary.

As preliminarily indicated, the above described use of the presentcontrol system on a film printer is intended to be illustrative ratherthan limiting in nature. It will be obvious that the control system hasa wide variety of other .uses and applications and may be regarded ashaving general utility in the field of automatic control.

Accordingly, the invention is intended to be limited only by the spiritand scope of the following claims.

We claim:

1. In an automatic control system, the combination of a control tapehaving a blank leader portion and a trailing portion formed with codedgroups of control perforation, a tape reader including electrical feedmeans for feeding said tape through the reader and a group of electricalcontacts which remain open in the absence of control perforations in theportion of the tape aligned with the reader and are selectively closedwhen a coded group of perforations is aligned with said reader, a groupof relays each associated with a particular reader contact, meansincluding said reader contacts for energizing each relay in response toclosure of its respective reader contact, each relay including a firstset of normally open holding contacts, a holding circuit including saidrelay contacts for locking each relay in its energized state uponclosure of its respective holding contacts, each relay including asecond set of contacts which occupy a first position when the respectiverelay is energized and a second position when the respective relay isdeenergized, an electrical circuit including the second sets of contactsof said relays for energizing said feed means to continuously feed saidtape through said reader when all of the second sets of contacts occupysaid first position and deenergizing said feed means to terminatefeeding of said tape through said reader upon movement of any one ormore of said second sets of contacts to said second position, vherebysaid blank leader portion of the tape is continuously fed through thereader to the first coded group, means for thereafter selectivelyenergizing said feed means to advance said tape through said reader fromone coded group to the next, and means for momentarily opening saidholding circuit in response to opening of said reader contacts duringadvancing of said tape from each coded group to the following codedgroup and subsequent closure of any one or more of the reader contactsby said following coded group.

2. In an automatic control system, the combination of a control tapehaving a blank leader portion and a trailing portion formed with codedgroups of control perforations, a tape reader including electrical feedmeans for feeding said tape through the reader and a group of electricalcontacts which remain open in the absence of control perforations in theportion of the tape aligned with the reader and are selectively closedwh n a coded group of perforations is aligned with said reader, a groupof relays each associated with a particular reader contact, meansincluding said reader contacts for energizing each relay in response toclosure of its respective reader contact, each relay including a firstset of normally open holding contacts, a holding circuit including saidrelay contacts for locking each relay in its energized state uponclosure of its respective holding contacts, each relay in cluding asecond set of normally closed contacts, an electrical circuit includingthe second sets of contacts of said relays for ener izing said feedmeans to continuously feed said tape through said reader when all of thesecond sets of contacts are closed and deenergizing said feed means toterminate feeding of said tape through said reader upon opening of anyone or more of said second sets of contacts, whereby said blank leaderportion of the tape is continuously fed through the reader to the firstcoded group, means for thereafter selectively energizing said feed meansto advance said tape through said reader from one coded group to thenext, and means for momentarily opening said holding circuit in responseto opening of said reader contacts during advancing of said tape fromeach coded group to the following coded group ant subsequent closure ofany one or more of the reader contacts by said following coded group.

3. In an automatic control system, the combination of a control tapehaving a blank leader portion and a trailing portion formed with codedgroups of control perforations, a tape reader including electrical feedmeans for feeding said tape through the reader and a group of electricalcontacts which remain open in the absence of control perforations in theportion of the tape aligned with the reader and are selectively closedwhen a coded group of perforations is aligned with said reader, a groupof relays each associated with a particular reader contact, meansincluding said reader contacts for energizing each relay in response toclosure of its respective reader contact, each relay including a firstset of normally open holding contacts, a holding circuit including saidrelay con tacts for locking each relay in its energized state uponclosure of its respective holding contacts, each relay including asecond set of normally closed contacts, an electrical circuit includingthe second sets of contacts of said relays connected in electricalseries therein for energizing said electrical feed means to continuouslyfeed said tape through said reader when all of the second sets ofcontacts are closed and deenergizing said electrical feed means toterminate feeding of said tape through said reader upon opening of anyone or more of said second sets of contacts, whereby said blank leaderportion of the tape is continuously fed through the reader to the firstl I. coded group, means for thereafter selectively energizing saidelectrical feed means to advance said tape through said reader from onecoded group to the next, and means for momentarily opening said holdingcircuit in response to opening of said reader contacts during advancingof said tape from each coded group to the following coded group andsubsequent closure of any one or more of the reader contacts by saidfollowing coded group,

4. In an automatic control system, the combination of a control tapehaving a blank leader portion and a trailing portion formed with codedgroups of control perforations, a tape reader including electrical feedmeans for feeding said tape through the reader and a group of electricalcontacts which remain open in the absence of control perforations in theportion of the tape aligned with the reader and are selectively closedwhen a coded group of perforations is aligned with said reader, a groupof first relays each associated with a particular reader contact, meansincluding said reader contacts for energizing each relay in response toclosure of its respective reader contact, a group of second relays eachassociated with a particular first relay, means including a set ofcontacts in each first relay for energizing the associated second relayin response to energizing of the respective first relay, each secondrelay including a first set of normally open holding contacts, a holdingcircuit including said holding contacts for locking each second relay inits energized state upon closure of its respective holding contacts,each second relay including a second set of contacts which occupy afirst position when the respective second relay is deenergized and asecond position when the respeotive second relay is energized, anelectrical circuit including the second set of contacts of said secondrelays for energizing said feed means to continuously feed said tapethrough said reader when all of the second sets of contacts of saidsecond relays occupy said first position and for deencrgiziug said feedmeans to discontinue feeding said tape through said reader in responseto movement of any one or more of said latter sets of contacts to saisecond position, whereby said blanl; leader portion of the tape iscontinuously fed through the reader to the first coded group, means forthereafter selectively energizing said feed means to feed said tape fromone coded group to the next, and means including a second set ofcontacts in each first rela r for momentarily opening said holdingcircuit in response to dcencrgizing of said first relays during feedingof the tape from one coded group to the following group and subsequentenergizing of any one or more of said first relays by said followinggroup. 5. In an automatic control system, the combination of a controltape having a blank leader portion and a trailing portion formed withcoded groups of control perform tions, a tape reader includingelectrical feed means for feeding said tape through the reader and agroup of electrical contacts which remain open in the absence of controlperforations in the portion of the tape aligned with the reader and areselectively closed when a coded group of perforations is aligned withsaid reader, a group of first rclays each associated with a particularreader contact, means including said reader contacts for energizing eachrelay in response to closure of its respective rea er contact, a groupof second relays each associated with a particular first relay, meansincluding a set of contacts in each first relay for energizing theassociated second relay in response to energizing of the respectivefirst relay, each second relay including a first set of normally openholding contacts, a holding circuit including said holding contacts forlocking each second relay in its energized state upon closure of itsrespective holding contacts, each second relay including a second set ofnormally closed contacts, an electrical circuit including the secondsets of contacts of said second relays connected in electrical seriesfor energizing said electrical feed means to continuously feed said tapethrough said reader when all of the second sets of contacts of saidsecond relays are closed and for deenergizing said electrical feed meansto discontinue feeding said tape through said reader in response toopening of any one or more of said latter sets of contacts, whereby saidblank leader portion of the tape is continuously fed through the readerto the first coded group, means for thereafter selectively energizingsaid electrical feed nae-ans to feed said tape from one coded group tothe next, and means for momentarily opening said holding circuit inresponse to deenergizin g of said first relays during feeding of thetape from one co ded group to the following group and subsequentenergizing of any one or more of said first relays by said followinggroup.

References Cited in the file of this patent UNITED STATES PATENTSBaldwin Aug. 1, 1944 Tholstrup Apr. 12, 1948 Nichols Mar. 15, 1949Buckley Feb. 27, 1951 Clark Oct. 30, 1951 1mm Nov. 27, 1951 Shively July16, 1957

1. IN AN AUTOMATIC CONTROL SYSTEM, THE COMBINATION OF A CONTROL TAPEHAVING A BLANK LEADER PORTION AND A TRAILING PORTION FORMED WITH CODEDGROUPS OF CONTROL PERFORATION, A TAPE READER INCLUDING ELECTRICAL FEEDMEANS FOR FEEDING SAID TAPE THROUGH THE READER AND A GROUP OF ELECTRICALCONTACTS WHICH REMAIN OPEN IN THE ABSENCE OF CONTROL PERFORATIONS IN THEPORTION OF THE TAPE ALIGNED WITH THE READER AND ARE SELECTIVELY CLOSEDWHEN A CODED GROUP OF PERFORATIONS IS ALIGNED WITH SAID READER, A GROUPOF RELAYS EACH ASSOCIATED WITH A PARTICULAR READER CONTACT, MEANSINCLUDING SAID READER CONTACTS FOR ENERGIZING EACH RELAY IN RESPONSE TOCLOSURE OF ITS RESPECTIVE READER CONTACT, EACH RELAY INCLUDING A FIRSTSET OF NORMALLY OPEN HOLDING CONTACTS, A HOLDING CIRCUIT INCLUDING SAIDRELAY CONTACTS FOR LOCKING EACH RELAY IN ITS ENERGIZED STATE UPONCLOSURE OF ITS RESPECTIVE HOLDINGS CONTACTS, EACH RELAY INCLUDING ASECOND SET OF CONTACTS WHICH OCCUPY A FIRST POSITION WHEN THE RESPECTIVERELAY IS ENERGIZED AND A SECOND POSITION WHEN THE RESPECTIVE RELAY ISDEENERGIZED, AN ELECTRICAL CIRCUIT INCLUDING THE SECOND SETS OF CONTACTSOF SAID RELAYS FOR ENERGIZING SAID FEED MEANS TO CONTINUOUSLY FEED SAIDTAPE THROUGH SAID READER WHEN ALL OF THE SECOND SETS OF CONTACTS OCCUPYSAID FIRST POSITION AND DEENERGIZING SAID FEED MEANS TO TERMINATEFEEDING OF SAID TAPE THROUGH SAID READER UPON MOVEMENT OF ANY ONE ORMORE OF SAID SECOND SETS OF CONTACTS TO SAID SECOND POSITION, WHEREBYSAID BLANK LEADER PORTION OF THE TAPE IS CONTINUOUSLY FED THROUGH THEREADER TO THE FIRST CODED GROUP, MEANS FOR THEREAFTER SELECTIVELYENERGIZING SAID FEED MEANS TO ADVANCE SAID TAPE THROUGH SAID READER FROMONE CODED GROUP TO THE NEXT, AND MEANS FOR MOMENTARILY OPENING SAIDHOLDING CIRCUIT IN RESPONSE TO OPENING OF SAID READER CONTACTS DURINGADVANCING OF SAID TAPE FROM EACH CODED GROUP TO THE FOLLOWING CODEDGROUP AND SUBSEQUENT CLOSURE OF ANY ONE OR MORE OF THE READER CONTACTSBY SAID FOLLOWING CODED GROUP.